What is true score theory and why is it important?

Question

What will be an ideal response?

Answer 1

True, score theory is a classical theory in measurement (and is often literally called classical test theory). Like all theories, you need to recognize that it is not proven; it is postulated as a model of how the world operates. Also, similar to many powerful models, the true score theory is a simple one. Essentially, true score theory maintains that every observable score is the sum of two components: true ability (or the true level) of the respondent on that measure; and random error. The true score is essentially the score that a person would have received if the score were perfectly accurate.

Why is true score theory important? For one thing, it is a simple yet powerful model for measurement. It is a reminder that most measurement will inevitably have an error component. Second, true score theory is the foundation of reliability theory, which will be discussed later in this chapter. A measure that has no random error (is all true score) is perfectly reliable; a measure that has no true score (is nothing but random error) has zero reliability. Minimizing measurement error is the key aim of developing measures that are more reliable. Third, true score theory can be used in computer simulations as the basis for generating observed scores with certain known properties.